Correlation between blood flow patterns and intimal hyperplasia at the distal end-to-side anastomosis

OBJECTIVE: To clarify the relationship between intimal hyperplasia and blood flow patterns in the host artery floor of the distal end-to-side anastomosis. MATERIALS AND METHODS: 32 dogs were used to construct 30 degrees, 45 degrees, 60 degrees and S-type anastomoses at the common carotid artery site with autogenous graft from the canine external jugular vein. Two months after operation, the bypassed arteries were harvested and histologic sections of the distal anastomoses were performed to determine the thickness of neointima. Flow patterns at the distal end-to-side anastomosis were analysed using particle image velocimetry (PIV) by rendering the bypassed arteries transparent. RESULTS: The averaged thicknesses of neointima in 30 degrees, 45 degrees, 60 degrees and S-type anastomoses were 45.26 +/- 5.99, 65.56 +/- 6.53, 119.50 +/- 10.30, 47.64 +/- 4.85 pin respectively vs 9.81 +/- 1.88 mu m in the control group. The flow patterns for different anastomotic angles were characterized by slow recirculation zones distal to the end-to-side anastomosis. The fluid velocity in the recirculation zone was the highest for the 30 degrees anastomosis and the slowest for 60 degrees anastomosis. CONCLUSION: Vascular intimal hyperplasia had a close relationship with blood flow patterns after bypass surgery. The larger the anastomotic angle, the thicker the intimal hyperplasia at the host artery floor of the distal end-to-side anastomosis.